Screw-pump.



EL S. BENNETT.

SCREW PUMP. APPLICATION FILED MAY 15, 1909.

I Patented Augso, 1910. .a auxin-SHEET 1.

'MQCJM E. S. BENNBITl SCREW PUMP. u PLIoATIoN FILED mma, 1909.

968,829; Patented Aug. 30,y 1910 Z SHEETB-SHEET 2.

w mmmJulMll llllllilllhi@ ERASTUS S. BENNETT, OF-NE`W 'FZEL N. Y.

SCREW-PUMP.

assen l'o all whom 'it may concern:

Be it known that l, Eaiisrus S. Bnn'nn'rr, citizen of the United States, residing at New York city, New York, have invented certain new and useful improvements in Screw-Pumps, of which the following isa specification.

My invention relates to the general form y of screw pump disclosed in application t'or Letters Patent or' the United States filed by me August Q8, 1908, .ttafiO'Ol ln said ap plication disclose means for eliminating the eiiect of slr-in Jfriction of the blades upon the body of water to'be forced, said means consisting ofa aphragm or diaphragme interposed in the screw blades or between the sections thereof, the said diaphragms having openings for the passage of the water forced by the blades.

My present improvement relates to means for holding these diaphragms in place, and' also to the construction of the openings through these diaphragme whereby an et fectual stop for the back drag or back pressure of the water, which results from the skin :friction existing between the blade 'l the body of water, or from other causes, is provided for and rendered practically negligible.

In the accompanying drawings Figure l is a sectional view through a screw pump embodying my invention; Fig. 2 is a view of one of the diaphragms within the cylinder; Fign 3 is a sectional View of Fig. 2; Figs. 4 ando are views similar to Figs. 2 and 3 of the diaphragm at the head ot' the cylinder; F ig. (3 is a detail view ot' one of the heads without a .diaphragm but with a division web; Fig. '7 is a sectional View in the nature of a diagram showing the ends of the screw blades 'in their relation to the diaphragmsu; Fig. 8 is a detail sectional View.

In these drawings, l indicates the inlet casing, 2 the outlet casing, 3 the pump cyl-- inder arranged between these casingsl. the screw piston, and 5 the diaphragm, of which there may be one or more,`accordiug to the extent or number of the screw blades. For holding these diaphragms in place, l provide a series of sleeves or collars 6 W'hich are' fitted to the interior of the cylinder and are interposed between the diaphragms and between the heads of the cylinder and the said diaphragme, these collars being long Specii'icaton ci Letters r'atent.

'Application filed I'fay 1:5, 3999.

vthe cylinder.

tfatented sei-.iai no. assess.

enough to separate the diaphragms and the heads t'or the proper amount of clearance for the working ot the screw' blades.

As in the application abovementioned, the eliect oit the use ot' the diaphragme is that the body of water having been forced longitudinally of the cylinder by one olf the screw blades, will be separated from this screw blade which has propelledit, so that it will be relieved of the back motion resulting from skin friction and may be acted on anew' by a second blade forming, in eidect, a continuation of the tirst blade section. The blade sections rotate in close proximity to the faces of the diaphragme so that, in the revolution of the screw, the blades Will cutoil' the water at the inlet openings and press this cut oil portion forward through the opening in the diaphragm, and immediately upon its passage through the diaphragm the eli'cct of skin friction will be eliminated and the body of water will loe subjected vto the action ot the next section of the screw blade, and so on throughout y"no collars t? lit tifrhtly in the cylinder and serve to properly ce the diaphragzns, and to hold then; against circumferential disi'ilacenient. lt will be ob served that the openings through the diaphragm are of conical `i'orin with the smaller end toward the discharge end ot the cylinder. By lthis construction l secure an automatic stop, or what may be called a water stop valve, for it will be understood that the column ot' water pressed through the openings will be equal in diameter to the smaller end ot the opening, and the water having passed throxwli, 'will find a haelt stop or arresting surtace on the plain face ot the diaphragm surrounding the contracted end of the opening, and any baclr pressure resulting from. the effect ot the inclined'blade on the water or from other causes will be taken up by this straight bearing and will be prevented from passing back through the diaphragm to the inlet side thereof.

In the operation of the device, any baolf' pressure existing in the water, by its actil upon the plain face of the diaphragm on itl discharge side, will set up eddy currents which will act across the smaller outlet ends of the nozzle-like openings and form a water lock at these points to prevent the vbackwa rd passage of Water or pressure from the discharge to the inlet side of the diaphragme and of the pump. The construction pro-` vides, in effect, an automatic check valve where we are dealing with water under pressure, or, more properly speaking, a water lock to prevent back flo It is evident that the water will be always under the heaviest pressure at the small end of the nozzle-shaped opening, and it is this pressure which must be overcome by the back pressure whether due to skin friction or to the head or column of water being forced or lifted before there can be any back' flow of water through the diaphragm, but, as set forth above, back pressure will form a water lock on the plain discharge side of the diaphragm, and this Ywater lock will increase in e `ect proportionately to the tendency to back pressure which the Water may have.

The tapering nozzle openings, at their larger ends, extend practically from the shaft or rather the hub of the screw blade to theinner periphery of the spacing rings so that they present no fiat obstructing surfaces on their inlet sides7 but they do present such surfaces on their outlet sides to pre ventl back flow. ,f

vAs will beseen from Figs. 2 and 3, the diaphragms have inner .and outer rings connected by spokes, and both the rings, as well as the spokes, taper toward their inlet sides. The same is true of the,diaphragms at the heads -of the cylinder., By this co`nstruction not only is no obstruction offered to the flow of the water, but the aggregate area of the openings through either diaphragm on the inlet side is equal to the area of the cross sectional inlet and outlet pipes minus the thickness of the spokes. By this construction a stream will be delivered approximately equal in cross sectional area to the cross sectional area'of the inlet or discharge pipe or of the cylinder. Y

The ring spacing of the diaphragms facilitates quick and accurate adjustment of the diaphragme in manufacturing. The rings .take the wear from the cylinder proper, and

are readily replaced. They also obviate the necessity for accurately boring the cylinder.

While the spokes or arms of the diaphragm are shown as radial, I do not confine myself in this regard. l

Instead of having an end head' provided with a vertical web dividing the inlet and the outlet, as shown in Fig. 6, I prefer ,to provide a diaphragmat each of these heads. In the construction shown in Fig. 6, the vertical web furnishes onlytwo `opposing surfaces to coperate with the screw blade. I have improved this construction by cutting the web or artition away at the face side of each headp so as to permit the insertion of adianhragm indicated at 5", lFigs. 1, 4 and rings.

shearing eii'ect on the water at the inlet end' of the apparatus, and` the forcing effect or what may he termed a plastering e'ect vat the discharge end where the screw blade forces the water forward through the head.

In this construction, a part of the 'vertical web used in my previous construction is dispensed with, and .the diaphragm takes its place. The openings through this head diaphragm are not necessarily of a. tapered form, though they should be tapered when the pump designed to work against pressure. In ease the head diaphragms are not cast with the heads, lthey will, of course, be set so that the vertical partitions of the diaphragme will register with the vertical edge of the dividing web .in the head. The diaphragme within the cylinder, as above stated, are heldin position by s` `acing These diaphragms are pre erably shouldered, leaving a projecting annular rim at 7 against which .the spacing rings abut. These spacing rings may be intact throughout the extent of each, or they may be split rings or formed in sections. Their edges tit between the shouldered portions of thediaphragms and the .interior periphery of the cylinder, or their edges may abut against the sides of shoulderless diaphragms.`

' The form or taper of the spokes of the diaphragm will depend upon the work the pump is intended to do, thus for volume pumping they are only `slightly tapered, whereas for pumping against strong back pressureor for lifting against a considerable head, they are tapered more sharply,A `In my improved arrangement with the tapered A openings, the area at the discharge end of the tapered openings is less than the area at the inlet, and this enables meto pump against a heavier back pressure or a greater head than would otherwise be the case. Each spoke in the diaphragme presents a knife edge to the incomin fluid.

In the form of t e invention having the web at the inlet and the web at the outlet,

the purpose ofthe web is to hold theiiuid cylinder, a screw piston and a diaphragm having an inner ring tapering from its outlet side to its inlet side and toward the axis.

of the piston, and an outer ring tapering from its voutletside, to lits inlet side and toward the cylinder wall, both of said rings on the outlet side of the diaphragm having anl exposed flat surface 'orf projection to form a back stop' for thewater after passing through the aphragm, the blade of the screw o erating close against said stop,'sub stantial y as described.

2. In combination in a screw pump, a cylinder, a' screw piston and a diaphragm having openings therethrough, the inner wallsof which taper from the outlet side to thefinlet side toward the axis ot' the piston and the Outer Walls of which incline from the outlet side to the inlet side toward the cylinder wall, said diaphragm on its outletV side having flat surfaces or projections to 4form a back stofJ for the water after passing through the. diaphragm, lthe blade of the screw operating vclose againstsaid stop. 3. In .combinatitn in 'a screw pump', a

cylinder, a screw piston therein, a diaphragm consisting cf an inner ring atthel hub of-,the piston, an outer ring at the cylinder and spokes connecting said rings, both the inner and outerA rings and the spokes tapering to the inlet ssde' of the diaphragm, and presenting tapered openings reaching 4 from the hub of the 'screw piston to the cylinder, 4and tapering from the inlet tothe outlet sides of the diapiragm, and with fiat surfaces exposed on the outlet side. about the openings substantia. ly as described 4. In combination a .c ylinder, a screw piston'therein, heads at'tlneends ofthe cylinder, diaphragms withii' the -cylinder and diaphragme at the heads having a plurality .o spokes to coperatewith the screw, said lastj mentioned diaphrigms being held in seats in the heads and having openings between the spokes tapered on all sides, substantially as described.

5. In combination in a pump, a cylinder, a screw piston therein, anv inlet and a discharge section and a division member or r spoke at the said inlet and outlet'coper ting with the screw piston, and eachbevel d on its -inlet side, the said screw `piston i operating close againstthe flat side of the' said inlet division member, substantially as described. l

6. In combination in a screw pump, a cylinder, a screw piston operatingtherein, a head connected with the cylinder, a division. wall or'web in said head providing a plurality of `passages leading to the cylinder,` a diaphragm interposed lbetween the said head andthe cylinder, said diaphragm having a plurality of openings extending' therethrough, substantially as described.

phragrris at the heads having a plurality of spokes to coperate with the screw, said last mentioned diaphragms being held in seats in the heads and having openings between the spokes ta 'ering on all sidesy substantially as descri ed.

In testimony whereof, I afliX my .signature in presence of two witnesses.

' .ER'AFTUS S. BENNETT.v Witnesses:

MYRoN L. JUSTIN, GEO. H. LiGI-rrroo'r. 

